Obesity has been shown to be associated with a poor prognosis in breast cancer patients. Survival time is decreased and recurrence rates are increased with greater obesity. Whether or not weight loss can have favorable effects on prognosis in obese breast cancer survivors is not known, and that is the ultimate question we would like to ask. As a first step, effective methods for weight loss need to be established in this population. We started a pilot study with internal funds develop an individualized approach towards weight loss in obese breast cancer survivors, and preliminary data is encouraging. We would like to be able to extend this study for a full 18 months and analyze the blood samples that are being collected for markers of cancer risk. Forty eight obese cancer survivors have been enrolled. At baseline, a psychiatric evaluation was obtained for each women and questionnaires on diet, health, exercise and psychosocial factors were administered. Since we are asking women to make large lifestyle changes, we would like to extend the intervention for a full year (instead of 6 months) and add a 6-month follow-up point to examine maintenance of weight loss. A better understanding of the influence of behavioral factors on weight loss should help us design a successful larger study with recurrence as the endpoint. As a secondary aim, we propose to analyze the blood samples collected for markers of cancer risk which are expected to be affected by weight loss: oxidative DNA damage, insulin-like growth factor 1 (IGF-1), and IGF-binding protein 3. The extent of changes in these markers will be compared with other plasma measures that are known to be affected by weight loss: leptin, glucose, lipids and triglyceride levels. This study should be useful to determine certain psychosocial are associated with extent of weight loss, and in turn whether weight loss is associated with changes in selected markers of breast cancer risk.